TWI663284B - Improved defect control and stability of dc bias in rf plasma-based substrate processing systems using molecular reactive purge gas - Google Patents

Abstract

A substrate processing system includes an upper electrode and a lower electrode arranged in a processing chamber. The gas delivery system selectively delivers at least one of a precursor, one or more deposition carrier gases, and a post-deposition flushing gas. While the precursor and the one or more deposition carrier gas systems are delivered by a gas delivery system, the RF generation system generates between the upper and lower electrodes in the processing chamber by supplying RF voltage to one of the upper and lower electrodes. RF plasma is used to deposit a film on the substrate. While the post-deposition flushing gas system is delivered by the gas delivery system, the bias generating circuit selectively supplies a DC bias voltage to one of the upper electrode and the lower electrode. The post-deposition flushing gas delivered by the gas delivery system contains a molecular reactive gas.

Description

Use of molecular reactive flushing gas to improve defect control and stability of DC bias in RF plasma-based substrate processing systems

The content of this disclosure is part of the serial application of US Patent Application No. 14 / 300,854 filed on June 10, 2014. The entire disclosure of the aforementioned application is incorporated herein by reference.

This disclosure relates to a substrate processing system, and more specifically, to defect control in a substrate processing system using an RF plasma and a reactive post-deposition gas.

The background description provided herein is for the purpose of generally presenting the background of the disclosure. The work results of the inventors currently listed, the scope described in this background section, and the implementation aspects that may not otherwise qualify as a description of prior art at the time of application, are not explicitly or implicitly acknowledged to be the subject of this disclosure Previous technology.

A substrate processing system for performing deposition and / or etching typically includes a processing chamber having a pedestal. A substrate (such as a semiconductor wafer) may be disposed on the base. For example, in a chemical vapor deposition (CVD) or atomic layer deposition (ALD) process, a gas mixture containing one or more precursors may be introduced into a processing chamber to deposit a film on a substrate Or etch the substrate.

In some substrate processing systems, radio frequency (RF) plasma can be used to activate chemical reactions. CVD and ALD systems using plasma are called plasma enhanced CVD (PECVD, plasma-enhanced CVD) and plasma enhanced ALD (PEALD, plasma-enhanced ALD). Some chemical reactions that occur in the gas phase cause nucleation, aggregation, and / or coalescence of particles within the reaction volume of the RF plasma. When the RF plasma system is turned on, the particles remain suspended in the RF plasma. Due to the balance of the forces acting on the particles, the particles do not fall on the substrate. For example: electrostatic repulsion forces the plasma boundary or plasma sheath of particles suspended in an RF plasma.

After the RF excitation system is turned off, particles may fall on the substrate. Therefore, most substrate processing systems evacuate the processing chamber by pumping out residual gas for a predetermined period. During this predetermined period, particles settle down in the processing chamber or are evacuated by the pump.

The substrate processing system includes an upper electrode and a lower electrode arranged in a processing chamber. The gas delivery system is configured to selectively deliver at least one of a precursor, one or more deposition carrier gases, and a post-deposition flushing gas. The RF generation system is configured to supply the RF voltage to one of the upper electrode and the lower electrode while the precursor and the one or more deposition carrier gas systems are delivered by the gas delivery system in the processing chamber. An RF plasma is generated between the lower electrodes and a film is deposited on the substrate. The bias generating circuit is configured to selectively supply a DC bias voltage to one of the upper electrode and the lower electrode while the post-deposition flushing gas system is delivered by the gas delivery system. The post-deposition flushing gas delivered by the gas delivery system contains a molecular reactive gas.

In other features, the post-deposition flushing gas does not include an inert gas. The post-deposition flushing gas system is selected from one of the deposition carrier gases. The post-deposition flushing gas has a higher breakdown voltage than helium and argon at processing pressures from 0.2 Torr to 6 Torr. The starting of the DC bias voltage is started in one of a first predetermined period before the RF plasma is extinguished and a second predetermined period after the RF plasma is extinguished.

In other features, the substrate moving system is configured to move the substrate relative to the base when a DC bias voltage is generated. The substrate moving system includes a robot configured to move the substrate relative to the base.

The substrate processing tool includes N reactors, each of which includes a plurality of substrate processing systems, where N is an integer greater than 0. The substrate moving system includes an indexing mechanism configured to index substrates between a plurality of substrate processing systems of at least one of the N reactors when a DC bias voltage is generated. The bias generating circuit generates a DC bias voltage before the RF plasma goes out, and stops the DC bias voltage before the subsequent RF plasma is ignited. Except for a period of time when the RF plasma is ignited, the bias generating circuit continuously generates a DC bias voltage.

In other features, the RF generation system includes an RF generator that generates RF voltage and a matching and distribution network that connects the RF generator and one of the upper electrode and the lower electrode. The film includes a nitrogen-free antireflection film, the deposition carrier gas includes carbon dioxide and helium, and the post-deposition gas includes carbon dioxide. The film contains amorphous silicon, one or more deposition carrier gases include hydrogen molecules and helium, and a post-deposition flushing gas contains hydrogen molecules. The film includes an ashable hard mask, one or more deposition carrier gases include hydrogen molecules and helium, and a post-deposition flushing gas includes hydrogen molecules. The film includes silicon nitride, one or more deposition carrier gases include nitrogen molecules and ammonia, and a post-deposition flushing gas includes nitrogen molecules. The film includes silicon dioxide, one or more deposition carrier gases include nitrogen molecules and nitrous oxide, and a post-deposition flushing gas includes nitrogen molecules. The film includes silicon oxycarbide, one or more deposition carrier gases include carbon dioxide and helium, and the post-deposition flushing gas includes carbon dioxide.

A method of processing a substrate in a processing system, which includes selectively delivering at least one of a precursor, one or more deposition carrier gases, and a post-deposition flushing gas to a processing chamber; When the deposition carrier gas system is delivered, when an RF voltage is supplied to one of the upper electrode and the lower electrode, an RF plasma is generated between the upper electrode and the lower electrode in the processing chamber, and the deposited film is on the substrate; A bias generating circuit to selectively supply a DC bias voltage to one of the upper electrode and the lower electrode. The post-deposition flushing gas is delivered during at least a portion of the DC bias voltage. The post-deposition flushing gas contains a molecular reaction gas.

In other features, the post-deposition flushing gas does not include an inert gas. The post-deposition flushing gas system is selected from one of the one or more deposition carrier gases. Post-deposition flushing gases have higher breakdown voltages than helium and argon at process pressures from 0.2 Torr to 6 Torr. The starting of the DC bias voltage is one of a first predetermined period before the RF plasma is extinguished and a second predetermined period after the RF plasma is extinguished. The substrate moving system is configured to move the substrate relative to the base when a DC bias voltage is generated.

In other features, the method includes indexing the substrate when a DC bias voltage is generated. The method includes generating a DC bias voltage before extinguishing the RF plasma, and stopping the DC bias voltage before igniting a subsequent RF plasma. The method includes continuously generating a DC bias voltage except for a period of time when the RF plasma is ignited.

In other features, the film includes a nitrogen-free antireflection film, one or more of the deposition carrier gases include carbon dioxide and helium, and the post-deposition gas includes carbon dioxide. The film contains amorphous silicon, one or more deposition carrier gases include hydrogen molecules and helium, and a post-deposition flushing gas contains hydrogen molecules. The film includes an ashable hard mask, one or more deposition carrier gases include hydrogen molecules and helium, and a post-deposition flushing gas includes hydrogen molecules. The film includes silicon nitride, one or more deposition carrier gases include nitrogen molecules and ammonia, and a post-deposition flushing gas includes nitrogen molecules. The film includes silicon dioxide, one or more deposition carrier gases include nitrogen molecules and nitrous oxide, and a post-deposition flushing gas includes nitrogen molecules. The film includes silicon oxycarbide, one or more deposition carrier gases include carbon dioxide and helium, and the post-deposition flushing gas includes carbon dioxide.

Further areas of applicability of this disclosure will become apparent from the detailed description, the scope of patent applications, and the drawings. The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of the disclosure.

The RF plasma substrate processing system may apply a DC bias voltage to one of the upper electrode or the lower electrode in accordance with the timing of the RF plasma. In some examples, the DC bias voltage is applied before the RF plasma is extinguished, and is maintained until after the RF plasma is extinguished. In some examples, the DC bias voltage is applied after the RF plasma is extinguished. The DC bias voltage changes the trajectory of the charged particles during the evacuation of the processing chamber, and reduces the number of defects on the substrate caused by particles suspended in the RF plasma during the extinguishing period. When the DC bias voltage is applied to the upper electrode or the lower electrode, the substrate can be moved or indexed according to the needs of the processing system.

The DC bias voltage generates an electrostatic field that moves particles away from the substrate when the substrate moves inside the tool. Inert noble gases such as helium and argon are commonly used as post-deposition flushing gases in PEALD and PECVD processes. However, processes using helium and argon as post-deposition flushing gases are sensitive to DC bias voltage systems due to the formation of luminous discharges under typical process conditions (such as pressure, gas flow, and voltage) within the processing chamber. Therefore, the DC bias voltage used to reduce particle contamination is unstable to these post-deposition flushing gas systems, and improved defect performance occurs. The substrate processing system according to the present disclosure uses an alternative post-deposition flushing gas, which provides a stable DC bias voltage without any DC-assisted plasma discharge, and it reduces the defects of the substrate processing system for performing PECVD / PEALD deposition.

Referring now to FIG. 1A, an example of a substrate processing system 100 for performing deposition or etching using an RF plasma is shown. For example, substrate processing systems can be used to perform PEALD and PECVD. The substrate processing system 100 includes a processing chamber 102 that surrounds other components of the substrate processing system 100 and houses an RF plasma. The substrate processing system 100 includes an upper electrode 104 and a base 106 including a lower electrode 107. The substrate 108 is disposed above the base 106 between the upper electrode 104 and the lower electrode 107.

For example only, the upper electrode 104 may include a shower head 109 that introduces and distributes a process gas. The shower head 109 may include a rod portion including one end connected to the top surface of the processing chamber. The bottom portion is generally cylindrical and extends radially outward from the other end of the rod at a certain distance from the top surface of the processing chamber. The surface of the bottom portion of the shower head facing the substrate includes a plurality of holes. Alternatively, the upper electrode 104 may include a conductive plate and the processing gas may be introduced in another manner. The lower electrode 107 may be disposed in a non-conductive base. Alternatively, the base 106 may include an electrostatic chuck including a conductive plate as the lower electrode 107.

The RF generating system 110 generates and outputs an RF voltage to one of the upper electrode 104 and the lower electrode 107. The other of the upper electrode 104 and the lower electrode 107 may be DC ground, AC ground, or floating. For example only, the RF generation system 110 may include an RF voltage generator 111 that generates an RF voltage that is fed to the upper electrode 104 or the lower electrode 107 by a matching and distribution network 112.

As will be described further below, the bias generating circuit 113 generates a DC bias voltage in response to the on / off timing of the RF voltage and other timing parameters described below. In some examples, the bias generating circuit 113 may further include a DC voltage supply 114 that provides a DC voltage signal. The bias generating circuit 113 may further include a synchronization circuit 115 that turns on / off the DC voltage signal in response to the RF on / off signal. The synchronization circuit 115 determines the timing of the DC bias voltage based on the timing of the RF on / off signal. In some examples, the synchronization circuit 115 applies a delay to the transition of the RF on / off signal to determine the starting point of the DC bias voltage. The duration of the DC bias voltage can also be set. In some examples, a DC bias voltage is applied to an electrode receiving an RF voltage to generate an RF plasma.

An example of a gas delivery system 130 is shown in FIG. 1A. The gas delivery system 130 includes one or more gas sources 132-1, 132-2, ..., and 132-N (collectively referred to as the gas source 132), where N is an integer greater than 0. The gas source supplies one or more precursors and mixtures thereof. The gas source can also supply flushing gas. Vaporized precursors can also be used. The gas source 132 is controlled by valves 134-1, 134-2, ..., and 134-N (collectively referred to as valve 134) and mass flow controllers 136-1, 136-2, ..., and 136-N (collectively referred to as mass The flow controller 136) is connected to the manifold 140. The output of the manifold 140 is fed into the processing chamber 102. For example only, the output of the manifold 140 is fed to the showerhead 109.

The heater 142 may be connected to a heater coil (not shown) disposed in the base 106. The heater 142 may be used to control the temperature of the susceptor 106 and the substrate 108. Valves 150 and pumps 152 may be used to evacuate the reactants from the processing chamber 102.

The controller 160 may be used to control elements of the substrate processing system 100. The controller 160 sends an RF plasma on / off signal to the RF generation system 110 and the synchronization circuit 115. The controller 160 can also set the timing parameters of the DC bias voltage, such as the initial or final on time or delay time relative to the RF plasma on / off signal.

For example only, the DC bias voltage may be a DC voltage having a value of 100 to 600 volts and a positive or negative polarity. The DC bias voltage creates an electrostatic field that changes the trajectory of the charged particles suspended in the plasma when the RF plasma system is turned off. After turning off the RF plasma, these particles are still charged because they are immersed in the RF plasma. At the same time, the processing chamber can be evacuated. The trajectory of the charged particles affected by the DC bias can bypass the substrate on the path from the charged particles to the pump port, effectively protecting the substrate from contamination.

Referring now to FIG. 1B, an example of the bias generating circuit 113 is shown. The bias generating circuit 113 includes a delay circuit 164 to store one or more delay times based on the transition of the RF plasma on / off signal. The bias generating circuit 113 includes a time on circuit 166 to store one or more durations of one or more DC bias voltages. The output of the delay circuit 164, the on-time circuit 166, and the RF on / off signal are input to the switch driver 168, which generates a switch driving signal to turn the switch 170 on and off when needed to provide a DC bias voltage. In some examples, the output of the synchronization circuit 115 is isolated from the RF voltage by an optional low-pass filter (LPF) 180.

For example only, the switch driver 168 includes a trigger circuit that is enabled by transitioning to RF on or RF off. Once triggered, the switch driver 168 waits for a delay period set by the delay circuit 164. After the delay period, the switch driver 168 turns on the DC bias voltage by closing the switch 170 for an open time period, which is set by the open time circuit 166. After this on-time period, the switch driver 168 turns off the switch 170 to turn off the DC bias voltage. As can be appreciated, the DC bias voltage can be triggered in any other suitable manner.

Referring to Figure 2-3, examples of timings of various DC bias voltages are shown. In FIG. 2, an example of the timing of the DC bias voltage is shown relative to the RF plasma signal, the substrate indexing or moving signal, and the gas supply signal. Typically, one or more gas or vapor precursors will be supplied when the RF plasma is turned on. A flushing gas containing a molecular reactive gas (instead of an atomic inert gas such as argon or helium) may be supplied when the RF plasma is turned off and / or when the DC bias is turned on, as will be described further below.

In some examples, the DC bias voltage 200 is activated before the RF plasma signal is terminated and continues until after the RF plasma signal is terminated. The timing of the DC bias voltage 200 may be based on the delay time t ₀ from the RF voltage. The timing of the DC bias voltage 200 overlaps the period t ₁ with the RF voltage, and the timing of the DC bias voltage 200 has a duration t ₂ and continues for a period (t ₂ -t ₁ ) after the RF voltage stops.

In some examples, a DC bias voltage is supplied and the substrate is indexed or otherwise moved at the same time. In particular, the substrate indexing or moving signal 210 may be generated in an overlapping manner during the DC bias voltage and after the RF voltage is stopped (for example, the period t ₅ after the RF voltage is stopped). Indexing or movement can be done before or after the falling edge of a DC bias voltage, such as a DC bias voltage of 200.

In addition, another DC bias voltage 215 may be supplied before the subsequent RF plasma is ignited and terminated shortly after the RF plasma is ignited. The DC bias voltage 215 in FIG. 2 precedes the RF voltage for a time t ₃ and has a duration t ₄ .

In FIG. 3, the DC bias voltage may also be supplied at other times during substrate processing. For example: The DC bias voltage 216 in FIG. 3 may be continuously supplied except for the period t ₆ when the RF plasma is ignited. For illustrative purposes, the indexing or mobile signal is delayed by a period t ₇ and has a longer duration t ₈ than the indexing or mobile signal in FIG. 2.

In the example of FIGS. 1A-3, a DC bias voltage is supplied to the upper electrode 104. In this example, the DC bias voltage may be a positive DC voltage or a negative DC voltage. The voltage polarity is selected experimentally and can be based on the structure (design and size) and processing conditions of the processing system. As can be appreciated, a DC bias voltage may be supplied to the lower electrode 107 instead of the upper electrode. The DC bias voltage can be supplied to the same electrode as an RF voltage, or to a different electrode as long as the different electrodes are not grounded.

Referring now to FIG. 4A, the substrate processing system 100 may be implemented in a tool 220 including multiple reactors, each of which has multiple substrate processing systems. The substrate enters the tool 220 from a cassette, which is loaded via a wafer transfer pod (221) such as a front opening unified pod (FOUP). The robot 224 includes one or more end effectors to process the substrate. The robot 224 is usually under atmospheric pressure. The robot 224 moves the substrate from the cassette to the load lock portion 230. For example, the substrate enters the load lock portion 230 via the port 232 and is placed on the load lock base 233. The port 232 connected to the atmospheric environment is closed and the load lock 230 is evacuated to an appropriate pressure for transfer. Then, port 234 is opened and another robot 236 (also has one or more hands) passes through port 237-1 corresponding to the selected reactors 240-1, 240-2, and 240-3 (collectively referred to as reactor 240). One of the substrates 237-2, 237-3 (collectively referred to as port 237).

The substrate indexing mechanism 242 can be used to further place a substrate relative to the substrate processing chamber. In some examples, the indexing mechanism 242 includes a mandrel 244 and a transfer disk 246.

The workstations of at least some of the reactors 240 correspond to the substrate processing system 100. The substrate processing system 100 of the reactor 240 is capable of performing semiconductor processing operations, such as material deposition or etching, sequentially or simultaneously with other workstations. At least some (and often all) workstations perform RF-based semiconductor processing operations. The substrate is moved from one workstation to the next workstation in the reactor 240 using a substrate indexing mechanism 242. One or more workstations of the reactor 240 may be capable of performing RF plasma deposition or etching. During use, the substrate system moves to the reactor 240 for processing and returns to the wafer transfer cassette 221. As can be appreciated, reducing the handling time of each substrate improves productivity and throughput.

Referring now to FIG. 4B, the tool controller 250 may communicate with one or more controllers 254 that are associated with various workstations of the reactor 240. Alternatively, the tool controller 250 and the controller 254 may be combined. The tool controller 250 also communicates with the robots 224 and 236 and the indexing mechanism controller 262 to coordinate the movement of the substrate and the indexing of the substrate in the respective reactors 240.

Referring now to FIG. 5, the movement of the substrate may also be performed only by the robot instead of the robot and the indexing mechanism. The substrate is delivered to one port of the transfer cavity 274. The transfer chamber 274 evacuates the pressure therein to an appropriate level. Then, another port connected to the transfer chamber 274 is opened, and one or more robots 276 of the hand end 278 deliver substrates to a plurality of processing chambers 280-1, 280-2, ..., and 280-P (collectively referred to as processing chamber 280 ), Where P is an integer greater than 1. The robot 276 can move along the track 279. The robot 276 delivers the substrate onto one of the plurality of bases 282-1, 282-2, ..., and 282-P corresponding to a selected one of the processing chambers 280.

6A, an example of a method 320 is shown. In 330, the control program decides whether or not the process starts. If so, the control routine proceeds to 332 and one or more substrates are configured on one or more pedestals that are associated with one or more processing chambers. In 336, the control program ignites the RF plasma and flows the precursor for a predetermined period in one or more processing chambers. In 338, the control program extinguishes the RF plasma and stops the precursor flow. At 342, a control program flows a flushing gas, which contains a molecular reactive gas instead of an atomic inert gas. In 346, the control program supplies the DC bias voltage for a predetermined bias period after the RF plasma goes out. In some examples, the predetermined bias period is stopped before the next RF plasma is ignited.

In 350, the control program determines whether there are additional RF plasma cycles before indexing or other substrate movements occur. If yes, control returns to 336. Otherwise, the control program decides whether indexing or other movement is required. If 354 is true, control continues to 358 and the substrate is indexed or otherwise moved during the bias cycle, the DC bias is turned off at 359 and then returned to 336. Otherwise, the control routine continues to 360 and the substrate is unloaded.

6B, an example of a method 420 is shown. In 430, the control program decides whether or not the process starts. If so, the control routine proceeds to 432 and one or more substrates are configured on one or more pedestals that are associated with one or more processing chambers. In 436, the control program ignites the plasma and flows the precursor for a first predetermined period in one or more processing chambers. In 437, the control program supplies the DC bias voltage for a predetermined bias period, and the bias voltage period begins before the end of the first predetermined period (and the RF plasma system is turned off). In some examples, the predetermined bias period is stopped before the subsequent RF plasma is ignited. At 438, the control program extinguishes the RF plasma and stops the precursor flow. At 442, a control program flows a flushing gas that contains a molecular reactive gas instead of an atomic inert gas. In 450, the control program determines whether there are additional RF plasma cycles before indexing or other substrate movement occurs. If yes, control returns to 436. Otherwise, the control program decides whether indexing or other movement is required. If 454 is true, control continues to 458 and the substrate is indexed or otherwise moved, the DC bias is turned off at 459 and then returns to 436. Otherwise, the control routine continues to 460 and the substrate is unloaded.

Referring now to FIG. 7, the number of defects on the substrate is reduced by supplying a DC bias voltage and using a flushing gas that contains a molecular reactive gas instead of an atomic inert gas. At 500, the number of defects processed when the DC bias voltage is not supplied during the substrate movement is displayed, and at 520, the number of defects processed when the DC bias voltage is supplied during the substrate movement is displayed. Applying a DC bias voltage during the movement of the substrate eliminates non-productive waiting times, which is usually required to pump out residual gas and precipitate gaseous particles before movement occurs.

This disclosure further reduces substrate defects by using a DC bias voltage to spray a flushing gas, which is compatible with the film / film deposition process. Inert noble gases such as helium (He) and argon (Ar) are commonly used as chamber flushing gases in PECVD / PEALD systems. In N _{2 free} films (such as nitrogen-free anti-reflection layer (NFARL), amorphous silicon (a-Si), and ashable hard mask (AHM) films) In this case, the DC bias voltage tends to be unstable when the inert gas (such as He and Ar) is used as the flushing gas. When He and Ar are used as flushing gases, DC-assisted plasma discharge occurs, which results in a high defect count.

Referring now to FIG. 8, an example of DC bias voltage behavior is shown, in which He is used as a purge gas after the NFARL film deposition process. Once the DC injection is supplied (-350 V in this example), the DC bias voltage reaches the maximum negative voltage value and then gradually decreases in value. Without being limited by a particular theory, the reduction in value may be the result of a voltage division, which is formed between the resistance element of the electrode system and the resistance of the plasma. The DC loss is also supported by the appearance of a plasma glow from the DC power supply between the electrodes. Similar results occur when replacing helium with argon.

Without being limited by a specific theory, the possible mechanism for the plasma bias voltage and plasma discharge of noble gases (such as He, Ar, etc.) is that these inert atomic gases have a low break down volrage, which under typical process conditions This is advantageous for plasma glow systems. Plasma glow is enhanced by long-lived, high-energy species of inert noble gases typically produced by DC excitation. The presence of uncontrolled DC plasmas between the upper and lower electrodes leads to increased defects. In addition, the hole pattern of the shower head can be seen within the defects appearing on the substrate.

In order to reduce the uncontrolled DC plasma during the DC bias, the inert rare-atom flushing gas system was replaced with a molecular reactive gas. For example only, some NFARL processes use both helium and CO ₂ as deposition gases. In some examples, carbon dioxide (CO ₂ ) can also replace helium as a post-deposition flushing gas to improve the stability of the DC bias voltage and reduce defects.

Referring now to FIGS. 9, 10A, and 10B, the improvement in the number of defects can be obtained by selecting a suitable post-deposition flushing gas, such as a molecular reaction gas, which is used while applying a DC bias voltage to reduce the number of particles. For example, when CO _{2 is} used instead of He used in the NFARL process of FIG. 8, the DC bias voltage is stable as shown in FIG. 9. In FIG. 10A, an NFARL film using He as a post-deposition flushing gas is shown. In FIG. 10B, when CO ₂ is used, the NFARL film system is shown to have a significantly reduced number of defects compared to FIG. 10A.

The test / simulation was repeated with He and Ar under backwash pressure (0.2 to 6T) and gas flow rate (1 to 10 slm). Under these conditions, instability of the DC bias voltage and luminescent plasma discharge were also observed. However, when CO ₂ was used as the post-deposition flushing gas, the DC bias voltage was stable, and the plasma excitation via the DC bias voltage was not observed in the PECVD reactor.

11-12, an example of a DC bias generating system is shown. In FIG. 11, an alternative circuit configuration 600 for generating a DC bias signal is shown. The tool controller 610 sends a control signal to the DC power supply 618 to supply a DC bias voltage. The tool controller 610 also sends a control signal to the input / output controller 614, which controls the synchronization circuit 622, the RF generator 632, and the RF matching circuit 636. The output (DC bias signal) of the synchronization circuit 622 is filtered by the RF filter 628, which is input to the RF distribution circuit 640 in combination with the output of the RF matching circuit 636. The RF distribution circuit 640 provides outputs to electrodes 642 and 644, such as, for example, a showerhead or electrode embedded in a base. In FIG. 12, the synchronization circuit 622 may include a polarity controller 650 that controls the polarity of the DC bias signal and an on / off controller 655 that is based on the control from the input / output controller 614 when needed. The signal turns the DC bias on and off.

Although the above is related to NFARL membranes and various post-deposition flushing gases, other membrane types also benefit from selecting molecular reaction gases as post-deposition flushing gases. For amorphous silicon (a-Si), He and H ₂ are typically used as deposition carrier gases, and hydrogen molecules (H ₂ ) are used as post-deposition flushing gases. For ashable hard masks (AHM), He and H ₂ systems are used as deposition carrier gases and H ₂ systems are used as post-deposition gases. For silicon nitride (SiN), ammonia (NH ₃ ) and nitrogen molecules (N ₂ ) are used as a deposition carrier gas and N ₂ is used as a post-deposition gas. For SiO ₂ , N ₂ O and N ₂ are used as a deposition carrier gas and N ₂ is used as a post-deposition gas. For silicon oxycarbide (SiOC), CO ₂ and He are used as the deposition carrier gas and CO ₂ is used as the post-deposition gas.

The foregoing is merely illustrative in nature and is by no means intended to limit the disclosure, its application, or uses. The broad teachings of this disclosure can be implemented in a variety of ways. Therefore, although this disclosure contains specific examples, the true scope of this disclosure should not be so limited, as other modifications will become apparent after studying the scope of the illustrations, descriptions, and subsequent patent applications. When used herein, the phrase "at least one of A, B, and C" should be understood to mean the use of non-exclusive logical "or" logic (A or B or C) and should not be interpreted as meaning "A At least one of B, at least one of B, and at least one of C. " It should be understood that one or more steps in the method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure.

In some embodiments, the controller is part of the system, and the system may be part of the example described above. Such systems may include semiconductor processing equipment including more than one processing tool, more than one chamber, more than one platform for processing, and / or specific processing elements (wafer pedestals, airflow systems, etc.). These systems can be integrated with electronic equipment used to control the operation of these systems before, during, and after semiconductor wafer or substrate processing. An electronic device may be referred to as a "controller", which may control various elements or sub-portions of the more than one system. Depending on the system's processing needs and / or type, the controller can be programmed to control any process disclosed herein, including: process gas delivery, temperature settings (eg, heating and / or cooling), pressure settings, vacuum settings, power Settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, access to a tool and other transfer tools, and / or loading or interfacing with specific systems Wafer transfer at the lock section.

Broadly speaking, a controller can be defined as an electronic device that has various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurement, and so on. An integrated circuit may include a chip in the form of firmware that stores program instructions, a digital signal processor (DSP), a chip defined as a special application integrated circuit (ASIC), and / or one or more programs that execute program instructions (such as software) Microprocessor or microcontroller. Program instructions can be instructions that communicate with the controller in the form of various individual settings (or program files). These settings define operating parameters that perform special processes on the semiconductor wafer or system. In some embodiments, the operating parameter may be part of a recipe defined by a process engineer to one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafers One or more process steps are completed during the fabrication of the die.

In some embodiments, the controller may be part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be the whole or a part of the host computer system in the "cloud" or the fab, which allows remote access to the wafer processing. The computer can allow remote access to the system to monitor the current progress of manufacturing operations, check the history of past manufacturing operations, check trends or performance metrics from multiple manufacturing operations, change the parameters currently being processed, and set the Process steps, or start a new process. In some examples, a remote computer (such as a server) may provide process recipes to the system via a network, which may include a local area network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings that are then passed from the remote computer to the system. In some examples, the controller receives instructions in the form of data that explicitly specifies parameters for various processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that configures the controller to interface or control. Thus, as described above, the controllers may be decentralized, such as by including one or more decentralized controllers that are connected together by a network and operate toward a common goal, such as the processes and controls described herein . An example of a decentralized controller for this purpose would be one or more integrated circuits on a chamber that communicate with one or more integrated circuits at a remote location, such as at the platform level or as part of a remote computer , Which combines to control the process in the chamber.

Example systems can include, without limitation, a plasma etching chamber or module, a deposition chamber or module, a spin-rinsing chamber or module, a metal plating chamber or module, a clean room or module, a beveled etching chamber or module Group, physical vapor deposition (PVD) chamber or module, chemical vapor deposition (CVD) chamber or module, atomic layer deposition (ALD) chamber or module, atomic layer etching (ALE) atomic layer etch chamber or mold Modules, ion implantation chambers or modules, orbital chambers or modules, and any other semiconductor processing system that can be associated with or used in the manufacture and / or production of semiconductor wafers.

As described above, the controller may communicate with one or more other tool circuits or modules, other tool components, group tools, other tool interfaces, adjoining tools, adjacent, based on one or more process steps to be performed by the tool. A tool, a tool located throughout the factory, a host computer, another controller, or a tool for material transfer that carries a wafer container into and out of a tool location and / or load within a semiconductor manufacturing plant port.

100‧‧‧ substrate processing system

102‧‧‧Processing Room

104‧‧‧up electrode

106‧‧‧ base

107‧‧‧ Lower electrode

108‧‧‧ substrate

109‧‧‧Sprinkler

110‧‧‧RF generation system

111‧‧‧RF voltage generator

112‧‧‧ matching and distribution network

113‧‧‧ bias generating circuit

114‧‧‧DC voltage supply

115‧‧‧sync circuit

130‧‧‧Gas Delivery System

132‧‧‧Gas source

134‧‧‧valve

136‧‧‧mass flow controller

140‧‧‧ Manifold

142‧‧‧heater

150‧‧‧ valve

152‧‧‧Pu

160‧‧‧controller

164‧‧‧ Delay circuit

166‧‧‧Open Time Circuit

168‧‧‧Switch driver

170‧‧‧Switch

180‧‧‧ Low-pass filter

200‧‧‧DC bias voltage

210‧‧‧ Substrate indexing or moving signal

215‧‧‧DC bias voltage

216‧‧‧DC bias voltage

220‧‧‧Tools

221‧‧‧Wafer Transfer Box

224‧‧‧ Robot

230‧‧‧Load lock

232‧‧‧Port

233‧‧‧Load lock base

234‧‧‧Port

236‧‧‧ Robot

237‧‧‧Port

240‧‧‧ reactor

242‧‧‧ indexing agencies

244‧‧‧ mandrel

246‧‧‧transfer disk

250‧‧‧tool controller

254‧‧‧controller

262‧‧‧Indexing mechanism controller

274‧‧‧transfer cavity

276‧‧‧Robot

278‧‧‧hand

279‧‧‧ track

280‧‧‧treatment room

600‧‧‧Circuit Configuration

610‧‧‧tool controller

614‧‧‧I / O Controller

618‧‧‧DC Power Supply

622‧‧‧Sync Circuit

628‧‧‧RF Filter

632‧‧‧RF generator

636‧‧‧RF matching circuit

640‧‧‧RF distribution circuit

642‧‧‧electrode

644‧‧‧electrode

650‧‧‧polarity controller

655‧‧‧Turn controller on / off

This disclosure can be more fully understood from the detailed description and accompanying drawings, among which:

1A is a functional block diagram of an example of a substrate processing system according to the present disclosure;

1B is a functional block diagram of an example of a DC bias generating system according to the present disclosure;

Figures 2 and 3 are timing diagrams illustrating examples of timing of DC bias voltages relative to RF plasma signals, substrate graduations or mobile signals and gas supply signals;

4A-4B and 5 illustrate examples of substrate processing tools;

6A and 6B illustrate examples of a method of operating a substrate processing system according to the present disclosure;

FIG. 7 illustrates the number of defects on a substrate with and without a DC bias voltage treatment.

8 is a graph illustrating a DC bias voltage as a function of time for a substrate processing system using helium as a post-deposition flushing gas to deposit NFARL;

FIG. 9 is a graph illustrating a DC bias voltage as a function of time for a substrate processing system using carbon dioxide as a post-deposition flushing gas to deposit NFARL;

10A and 10B illustrate substrate defects processed according to FIGS. 8 and 9 respectively;

11 is a functional block diagram of an alternative circuit configuration for generating a DC bias signal; and

Figure 12 is a functional block diagram of an alternative synchronization circuit.

In the figures, reference numbers may be reused to identify similar and / or identical elements.

Claims (52)

A substrate processing system includes: a processing chamber; an upper electrode disposed in the processing chamber; a pedestal disposed in the processing chamber, wherein the pedestal is configured to support a substrate during processing, and wherein, the The base includes a lower electrode; an RF generating system configured to generate an RF plasma between the upper electrode and the lower electrode in the processing chamber by supplying an RF voltage to one of the upper electrode and the lower electrode; A bias generating circuit configured to selectively supply a DC bias voltage to one of the upper electrode and the lower electrode by: a first predetermined period before the RF plasma is extinguished and extinguished At least one of a second predetermined period after the RF plasma starts the supply of the DC bias voltage, and a third predetermined period after the RF plasma is extinguished and before a subsequent RF plasma is ignited At the same time, stopping the supply of the DC bias voltage; and a substrate moving system configured to generate a moving signal to move the substrate relative to the base when the DC bias voltage is generated. For example, the substrate processing system of claim 1 in the patent application scope, wherein the bias generating circuit includes: a DC voltage supply; and a synchronization circuit that communicates with the DC voltage supply and is configured to generate the DC bias voltage. For example, the substrate processing system of claim 2 in the patent application, wherein the bias generating circuit further includes a low-pass filter configured to filter an output of the synchronization circuit and has one of the upper electrode and the lower electrode connected. One of the outputs. For example, the substrate processing system of the first patent application scope, wherein the substrate moving system includes a robot configured to move the substrate relative to the base. A substrate processing tool includes: N reactors, each of which includes the substrate processing system of the first patent application scope, wherein N is an integer greater than 0, wherein the substrate moving system of the substrate processing system includes one minute The degree mechanism is configured to index the substrate between a plurality of workstations in at least one of the N reactors when the DC bias voltage is generated. For example, the substrate processing system of claim 1 in the patent scope, wherein the DC bias voltage and the RF voltage are both connected to one of the upper electrode and the lower electrode. For example, the substrate processing system of the first patent application scope, wherein the bias generating circuit is configured to generate the DC bias voltage at the first predetermined period before the RF plasma is extinguished, and the subsequent RF plasma is ignited. This DC bias voltage was stopped before. For example, the substrate processing system of claim 1 in which the bias voltage generating circuit is configured to generate the DC bias voltage at the second predetermined period after the RF plasma is extinguished, and ignite the subsequent RF plasma. This DC bias voltage was stopped before. For example, the substrate processing system of claim 1, wherein the bias generating circuit is configured to continuously generate the DC bias voltage except when the RF plasma system is ignited for a period of time. For example, the substrate processing system of the first patent application scope, wherein the RF generating system includes: an RF generator for generating the RF voltage; and a matching and distribution network connecting the RF generator and the upper electrode and The one of the lower electrodes. A substrate processing system includes: a processing chamber; an upper electrode disposed in the processing chamber; a base disposed in the processing chamber, wherein the base is configured to support a substrate, and wherein the base includes Lower electrode; an RF generating system configured to generate an RF plasma between the upper electrode and the lower electrode in the processing chamber by supplying an RF voltage to the upper electrode; a bias generating circuit configured to selectively Supplying a DC bias voltage to the upper electrode by starting the DC when at least one of a first predetermined period before the RF voltage stops or a second predetermined period after the RF voltage has stopped Bias voltage, and stopping the DC bias voltage at a third predetermined period after the RF voltage has stopped and before a subsequent RF voltage is started; and a substrate moving system configured to generate the DC bias voltage when A moving signal is generated to move the substrate relative to the base. For example, the substrate processing system according to item 11 of the patent application, wherein the bias generating circuit includes: a DC voltage supply; and a synchronization circuit that communicates with the DC voltage supply and is configured to generate the DC bias voltage. For example, the substrate processing system of claim 12 in the patent application, wherein the bias generating circuit further includes a low-pass filter configured to filter an output of the synchronization circuit and an output having a connection to the upper electrode. For example, the substrate processing system of the scope of application for patent No. 11 further includes a robot configured to move the substrate relative to the base, wherein the robot moves the substrate when the DC bias voltage is generated. A substrate processing tool, comprising: N reactors, each of which includes the substrate processing system for patent application No. 11, wherein N is an integer greater than 0; and an indexing mechanism configured to generate the DC bias voltage At that time, the substrate is indexed between a plurality of workstations in at least one of the N reactors. For example, the substrate processing system of claim 11 in which the bias generating circuit is configured to generate the DC bias voltage at the first predetermined period before extinguishing the RF plasma, and stop after extinguishing the RF plasma. The DC bias voltage. For example, the substrate processing system of claim 11 in which the bias generating circuit is configured to generate the DC bias voltage at the second predetermined period after the RF plasma is extinguished, and is ignited by a subsequent RF plasma This DC bias voltage was stopped before. For example, the substrate processing system of claim 11 in which the bias generating circuit is configured to continuously generate the DC bias voltage except when the RF plasma system is ignited. For example, the substrate processing system according to claim 11 of the patent application scope, wherein the RF generating system includes: an RF generator for generating the RF voltage; and a matching and distribution network connecting the RF generator and the upper electrode. For example, the substrate processing system of the first patent application scope, wherein the substrate moving system is further configured to generate the mobile signal that at least partially overlaps the DC bias voltage. A substrate processing system includes: an upper electrode and a lower electrode disposed in a processing chamber; a base disposed in the processing chamber, wherein the base is configured to support a substrate during processing; a gas delivery system, Configured to selectively deliver at least one of a precursor, one or more deposition carrier gases, and a post-deposition flushing gas; an RF generation system configured to displace the precursor and the one or more deposition carrier gas systems from the gas While the delivery system is delivering, an RF plasma is generated between the upper electrode and the lower electrode in the processing chamber by supplying an RF voltage to one of the upper electrode and the lower electrode to deposit a film on the substrate. And a bias generating circuit configured to selectively supply a DC bias voltage to one of the upper electrode and the lower electrode while the post-deposition flushing gas system is being delivered by the gas delivery system, wherein The post-deposition flushing gas delivered by the gas delivery system includes a molecular reactive gas. For example, the substrate processing system of the scope of application for patent No. 21, wherein the post-deposition flushing gas does not include an inert gas. For example, the substrate processing system according to claim 21, wherein the post-deposition flushing gas system is selected from one of the deposition carrier gases. For example, the substrate processing system of claim 21, wherein the post-deposition flushing gas has a higher breakdown voltage than helium and argon at a processing pressure from 0.2 Torr to 6 Torr. For example, the substrate processing system of claim 21, wherein the starting of the DC bias voltage is started at a first predetermined period before the RF plasma is extinguished and a second predetermined period after the RF plasma is extinguished. One of them. For example, the substrate processing system of the 21st patent application scope further includes a substrate moving system configured to move the substrate relative to the base when the DC bias voltage is generated. For example, the substrate processing system with the scope of application for patent No. 26, wherein the substrate moving system includes a robot, and is configured to move the substrate relative to the base. A substrate processing tool includes: N reactors, each of which includes a plurality of substrate processing systems in the scope of the patent application No. 26, wherein N is an integer greater than 0, wherein the substrate moving system includes an indexing mechanism, It is configured to index substrates between the plurality of substrate processing systems of at least one of the N reactors when the DC bias voltage is generated. For example, the substrate processing system of claim 21, wherein the bias generating circuit generates the DC bias voltage before the RF plasma is extinguished, and stops the DC bias voltage before a subsequent RF plasma is ignited. For example, the substrate processing system of claim 21, wherein the bias generating circuit continuously generates the DC bias voltage except for a period of time when the RF plasma system is ignited. For example, the substrate processing system with the scope of patent application No. 21, wherein the RF generating system includes: an RF generator for generating the RF voltage; and a matching and distribution network connecting the RF generator and the upper electrode and The one of the lower electrodes. For example, the substrate processing system of claim 21, wherein the film includes a nitrogen-free antireflection film, the deposition carrier gas includes carbon dioxide and helium, and the post-deposition flushing gas includes carbon dioxide. For example, the substrate processing system of claim 21, wherein the film includes amorphous silicon, the one or more deposition carrier gases include hydrogen molecules and helium, and the post-deposition flushing gas includes hydrogen molecules. For example, the substrate processing system of claim 21, wherein the film includes an ashable hard mask, the one or more deposition carrier gases include hydrogen molecules and helium, and the post-deposition flushing gas includes hydrogen molecules. For example, the substrate processing system according to claim 21, wherein the film includes silicon nitride, the one or more deposition carrier gases include nitrogen molecules and ammonia, and the post-deposition flushing gas includes nitrogen molecules. For example, the substrate processing system according to claim 21, wherein the film includes silicon dioxide, the one or more deposition carrier gases include nitrogen molecules and nitrous oxide, and the post-deposition flushing gas includes nitrogen molecules. For example, the substrate processing system according to claim 21, wherein the film includes silicon oxycarbide, the one or more deposition carrier gases include carbon dioxide and helium, and the post-deposition flushing gas includes carbon dioxide. A method for processing a substrate, processing a substrate in a substrate processing system, the method comprising: selectively delivering at least one of a precursor, one or more deposition carrier gases, and a post-deposition flushing gas to a processing chamber; When an RF voltage is supplied to one of an upper electrode and a lower electrode, an RF plasma is generated between the upper electrode and the lower electrode in the processing chamber, and the precursor and the one or more deposition carrier gases are simultaneously delivered, Depositing a film on the substrate; and selectively supplying a DC bias voltage to the one of the upper electrode and the lower electrode, wherein the post-deposition flushing gas is delivered during at least a portion of the DC bias voltage, And wherein, the post-deposition flushing gas includes a molecular reaction gas. For example, the method for processing a substrate according to claim 38, wherein the post-deposition flushing gas does not include an inert gas. For example, the method for processing a substrate according to claim 38, wherein the post-deposition flushing gas system is selected from one of the one or more deposition carrier gases. For example, the method for processing a substrate according to item 38 of the patent application, wherein the post-deposition flushing gas has a higher breakdown voltage than helium and argon at a processing pressure from 0.2 Torr to 6 Torr. For example, the method for processing a substrate according to item 38 of the patent application, wherein the starting of the DC bias voltage is started at a first predetermined period before the RF plasma is extinguished and a second predetermined after the RF plasma is extinguished. One of the cycles. For example, the method for processing a substrate according to item 38 of the patent application scope further includes moving the substrate relative to a base supporting the substrate when the DC bias voltage is generated. For example, the method for processing a substrate according to item 38 of the patent application scope further includes indexing the substrate when the DC bias voltage is generated. For example, the method for processing a substrate according to item 38 of the patent scope further includes generating the DC bias voltage before extinguishing the RF plasma, and stopping the DC bias voltage before igniting a subsequent RF plasma. For example, the method for processing a substrate according to item 38 of the patent application scope further includes continuously generating the DC bias voltage in addition to a period of time when the RF plasma is ignited. For example, the method for processing a substrate according to claim 38, wherein the film includes a nitrogen-free antireflection film, the one or more deposition carrier gases include carbon dioxide and helium, and the post-deposition flushing gas includes carbon dioxide. For example, the method for processing a substrate according to claim 38, wherein the film includes amorphous silicon, the one or more deposition carrier gases include hydrogen molecules and helium, and the post-deposition flushing gas includes hydrogen molecules. For example, the method for processing a substrate according to claim 38, wherein the film includes an ashable hard mask, the one or more deposition carrier gases include hydrogen molecules and helium, and the post-deposition flushing gas includes hydrogen molecules. For example, the method for processing a substrate according to claim 38, wherein the film includes silicon nitride, the one or more deposition carrier gases include nitrogen molecules and ammonia, and the post-deposition flushing gas includes nitrogen molecules. For example, the method for processing a substrate according to claim 38, wherein the film includes silicon dioxide, the one or more deposition carrier gases include nitrogen molecules and nitrous oxide, and the post-deposition flushing gas includes nitrogen molecules. For example, the method for processing a substrate according to item 38 of the application, wherein the film includes silicon oxycarbide, the one or more deposition carrier gases include carbon dioxide and helium, and the post-deposition flushing gas includes carbon dioxide.